In this project funded by the Chemical Synthesis program of the Chemistry Division, Professor Leslie Murray of the University of Florida is developing molecular systems that will mirror and improve our understanding of the reactivity of metal clusters found in numerous enzymes in biology. The biological metal clusters perform reactions ranging from the conversion of greenhouse gases (e.g., nitrous oxide or carbon dioxide) into benign products (e.g., water and nitrogen) or fuels (e.g., carbohydrates). Therefore, this project ultimately aims to develop bioinspired approaches to performing efficiently these types of reactions, all of which are of significant societal importance. This project also includes outreach to K-12 students.
The central hypothesis of this project is that high spin late 3d metal ions can react cooperatively in clusters to activate strong bonds and subsequently perform heteroatom transfer at relatively low energetic cost. This project focuses on using macrobicycles as ligands to support and template triiron clusters. These ligands provides steric protection for the three metal centers to afford low coordinate metal centers, which limits the formation of metal-metal bonds or strong interactions in the clusters and, simultaneously, templates an internal cavity for possible substrate binding. Upon chemical reduction, these triiron clusters can complex and activate dinitrogen by these compounds upon chemical reduction. Mechanistic studies of this reduction will involve changing reaction outcomes by introducing structural changes as well as examining the reactivity of intermediates with exogenous substrates (e.g., X-H bond activation). Reaction intermediates and products will be characterized by physical methods including X-ray crystallography, EPR spectroscopy, Mössbauer spectroscopy and X-ray absorption spectroscopy. An outreach program couples established university-based chemistry department programs with K-12 institutions that serve local students from predominantly underrepresented groups. The broader impacts of this work include the potential societal benefits from a fundamental understanding of how biological systems catalyze challenging reactions which relate to the development of new molecular approaches geared toward energy independence.
